GB2194308A

GB2194308A - Drive chain covers

Info

Publication number: GB2194308A
Application number: GB08719827A
Authority: GB
Inventors: Masashi Nagano
Original assignee: Shimano Industrial Co Ltd
Current assignee: Shimano Inc
Priority date: 1986-08-21
Filing date: 1987-08-21
Publication date: 1988-03-02
Anticipated expiration: 2007-08-21
Also published as: FR2603013B1; JPH0331669Y2; DE3727839A1; US4854924A; FR2603013A1; GB8719827D0; GB2194308B; JPS6332978U; IT8721686A0

Description

GB2194308A 1

SPECIFICATION spectively.

A cover means on the chain comprises a Drive chain covers plurality of first cover members or covers 3 for covering the pairs of the inner link plates The present invention relates to cover means 70 21, and a plurality of second cover members for a drive chain. The invention is especially, or covers 4 for covering the pairs of the outer but not exclusively, concerned with cover link plates 22. The first and second covers 3 means for the drive chain between a front and 4 may be different in configuration ac chain gear and a rear chain gear of a bicycle. cording to the link plates to be covered, but A bicycle drive chain is usually covered by a 75 in the present embodiment, they are mutually chain guard or casing to prevent a cyclist's identical.

clothing from being soiled by lubricant and/or Each of the covers 3 and 4 has an outside dirt on the chain. The chain casing is fixed to wall portion 11 spanning a pair of link plates the bicycle frame and is relatively bulky. Also, 21 or link plates 22; a pair of side wall por time and materials are required to mount the 80 tions 12 and 13 covering respective link casing on the bicycle frame. A full casing for plates 21 or 22; and a pair of retainer por covering the entire drive chain is complicated tions 14 and 15 which are laterally inwardly to assemble; and a half-casing for covering directed and engage with respective edge por only the upper run of the drive chain still al- tions of the link plates 21 or 22 opposite the lows some risk of soiling of the cyclist's 85 outside wall portion 11.

clothing. The covers 3 and 4 are of a plastics ma- An object of the invention is to provide an terial, for example polypropylene or synthetic improved cover means on a drive chain to rubber. The length L of each cover 3,4 is obviate or mitigate the shortcomings de- substantially equal to the distance between scribed above. 90 the pins 23 (chain pitch). The outside wall According to the present invention, there is portion 11 of each cover 3,4 has a width W provided a drive chain having laterally-spaced about equal to or slightly larger than the dis link plates, a cover means comprising a series tance across a pair of outer link plates 22, of cover members each having a cross-sec- and the side wall portions 12 and 13, as tional configuration comprising an outside wall 95 shown in Fig. 4, are outwardly convex to ac portion spanning a pair of link plates, a pair of commodate the drive chain parts.

side wall portions covering respective link The configuration of the side wall portions plates, and a pair of laterally inwardly directed 12 and 13, as viewed in side elevation, in retainer portions engaging respective edge cludes a rectangular sub- portion between the portions of the link plates opposite the out- 100 outside wall portion 11 and the line joining the side wall portion, all of said portions being link pin 23 centres, and a sub-portion having mutually integrally formed. convergent opposite sides 30, 31 to accom- Embodiments of the present invention will modate curvature of the drive chain without now be described, by way of example, with interference between mutually adjacent covers.

reference to the accompanying drawings in 105 As shown in Fig. 5, the convergent sides 30, which: 31 define end face portions of the cover Fig. 1 is a perspective view from above of member, and the points 30a and 3 la are co- part of a drive chain with cover means in incident with the axes of link pins 23. When accordance with the invention; the drive chain is transported in a curve as Fig. 2 is a perspective view from below of 110 when engaging with a chain gear FG (Fig. 7), the Fig. 1 embodiment; the link plates 21 and 22 rotate around the Fig. 3 is a partially cutaway side elevation pins 23 and the cover members likewise ro- of the embodiment of Figs. 1 and 2; tate, but do not interfere with each other Fig. 4 is an enlarged end elevation of a thanks to the convergent sides or end face cover member; 115 portions 30 and 31.

Fig. 5 is a sectional side elevation on the In a conventional roller chain, as shown, line V-V in Fig. 4; each link plate 21 or 22 is of waisted configu- Fig. 6 is a sectional plan view taken on the ration defined by opposed circular arcs inter- line VI-VI in Fig. 4; mediate the link ends, the latter being defined Fig. 7 is an illustration of a,chain drive hav- 120 by smaller circular arcs. The retaining portions ing a cover means according to the invention; 14 and 15 are formed to mate with this con- Fig. 8 is an enlarged end view of a modified ventional link configuration. Thus, curved sur- cover member; and faces 14b and 15b are formed at opposite Fig. 9 is a sectional side elevation on the ends of the retainer portions facing inwardly line IX-IX in Fig. 8. In the drawings, a drive 125 for mating engagement with the circular edges chain consists of pairs of opposite inner link of the link plate ends respectively. Hence, plates 21, pairs of opposite outer link plates when the covers 3 and 4 are mounted on the 22, connecting link pins for rotatably connect- link plates 21 and 22, the curved portions ing the pairs of link plates 21 and 22, and 14b and 15b locate on the link plates thereby rollers 24 supported on the link pins 23 re- 130 restraining the covers 3 and 4 from shifting 2 GB2194308A 2 lengthwise of the drive chain. Thus, the 6. A drive chain according to claim 5, covers 3 and 4 are held reliably to the chain wherein said locating means comprises a re without creating a backlash. cess accomodating an end portion of a link The first and second covers 3 and 4 may pin.

be made integral and the total length of them 70 7. A drive chain according to any one of may be made equal to double the interval beclaims 1 to 4, wherein each link plate has a tween the respective pins, thereby being re-entrant configuration and the inside of each mounted on the link plate 21 or 22. retainer portion is shaped to engage said reThe covers 3 and 4 may be provided and entrant configuration thereby to prevent shift- placed on a drive chain in different colour 75 ing of the cover member in the longitudinal It combinations according to desired appearance direction of the drive chain.

or effect. 8. A drive chain according to any one the As shown in Figs. 8 and 9, the inner sur- preceding claims, wherein mutually opposite faces of the side wall portions 12 and 13 are free edge portions of said retainer portions are provided at opposite ends with part-circular 80 formed to define therebetween a convergent recesses 12a and 13a engageable with the mouth for guiding approach of the associated connecting pins 23, so that the recesses 12a drive chain portion towards a chain gear.

and 13a accommodate the pin ends respec- 9. A drive chain according to any one of tively, thereby preventing the covers 3 and 4 the preceding claims, wherein each said cover from lengthwise shifting. 85 member is made from a material having yiel- The covers 3 and 4 define an open mouth dably resilient properties.

at the engaging side of the drive chain 2 with 10. On a drive chain, a cover means sub- the chain gear, and the retainer portions 14 stantially as hereinbefore described with refer and 15 are provided with rounded guide sur- ence to and as shown in Figs. 1 to 7 or Figs.

faces 14c and 15c as shown in Fig. 4, or 90 1 to 7 as modified by Figs. 8 and 9 of the slanted guide surfaces 14d and 15d as shown accompanying drawings.

in Fig. 8, thereby assisting the chain 2 to be guided smoothly to engage with the chain Published 1988 at The Patent Office, State House, 66/71 High Holborn, London WC1 R 4TP. Further copies may be obtained from gear. The Patent office, Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD.

Printed by Burgess & Son (Abingdon) Ltd. Con. 1/87.

Claims

1. On a drive chain having laterally-spaced link plates, a cover means comprising a series of cover members each having a cross-sec tional configuration comprising an outside wall portion spanning a pair of link plates, a pair of si e wall portions covering respective link plates, and a pair of laterally inwardly directed retainer portions engaging respective edge portions of the link plates opposite the out side wall portion, all of said portions being mutually integrally formed.

2. A drive chain according to claim 1, wherein the longitudinal dimension of each cover member is substantially equal to pitch of the drive chain.

3. A drive chain according to claim 2, wherein the configuration of each said side wall portion in side elevation comprises a rec tangular sub-portion between the outside wall portion and the line joining the link pin centres, and a sub-Portion having convergent opposite sides to accomodate curvature of the drive chain without interference between mu tually adjacent cover members.

4. A drive chain according to any one of claims 1 to 3, wherein each said side wall portion is of outwardly convex configuration as viewed in cross-section..

5. A drive chain according to any one of claims 1 to 3, wherein the inside of each side wall portion is provided with locating means engaging a part of the drive chain to prevent shifting of the cover member in the longitudi nal direction of the drive chain.